Musnad Ahmad 2:188

'Affan narrated to us, 'Abd al-Wahid narrated to us, Yazid al-Rishk narrated to us, from Mu'adhah, from Umm 'Amr bint 'Abd Allah, that she heard 'Abd Allah ibn al-Zubayr narrating that he heard 'Umar ibn al-Khattab delivering a sermon. He said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever wears silk in this world shall not be clothed in it in the Hereafter."